The invention relates to an intervertebral implant and to a method for spondylodesis of the lumbar vertebral column.
German Patent No. DE 199 57 339 C2 describes an intervertebral implant comprising a head which has a conical portion with an external thread, a central portion with an external thread, and a basic structure. The central portion is formed by a plurality of struts extending from the head to the basic structure, and thus large-area windows remain open between the head, the strut and the basic structure.
This known implant deliberately dispenses with the previously known sleeve-type form of intervertebral implants and instead uses a central portion with narrow struts which leave open an optimally large window. A large-area direct path from one vertebral body to another can be exposed in this manner for the spongiosa introduced into the intervertebral implant, and this allows a particularly good frictional connection and accelerates bone formation. In addition X-ray examination during and after an operation is more easily possible with intervertebral implants of this type.
With this known intervertebral implant the head comprises a cylindrical portion, which carries the external thread, and a conical, thread-free portion adjoining at the end region. With this known intervertebral implant it is a risk to carry out a complete distraction, in particular of the ventral circumference of the vertebral body. This is because there is some danger to damage the adjacent vena cava and the aorta.